1. Field of the Invention
The invention is related to apparatus for providing power steering assist to outboard motors and to inboard/outboard motor assemblies employing a control rudder supported in the slip stream and means to lock the steering mechanism directly to the motor assembly when the boat is moving below a preselected rate.
2. Description of the Prior Art
Most boats employ a motor assembly which is pivotally supported to the stern of the boat. These motor assemblies are of two basic types, that is, the outboard type in which the motor and power drive, including the propeller, are all arranged as a unit and, the second type, known as the inboard/outboard type in which the motor is mounted within the boat forward of the stern and a drive shaft extends through the stern to drive an outboard unit which is pivoted so as to apply turning direction to the boat.
In these typical arrangements the boats include a steering mechanism which is usually in the form of a steering wheel, although for some sport fishermen, a steering stick is utilized. Whether employing a steering wheel or a steering stick, a means is provided for positioning a steering member adjacent to the outboard drive assembly. The steering member is usually controlled by the steering wheel by means of cables, a flexible shaft, or a hydraulic system.
The usual means of steering an outboard or inboard/outboard type motorboat is to connect the steering member directly to the drive assembly. In the case of an outboard motor, the entire outboard motor unit is pivoted to provide steering; and in the case of the inboard/outboard arrangement, the outboard motor assembly is pivoted to steer the boat. This arrangement works completely satisfactory when the motor is of fairly low horsepower or when operating at high speeds. When high horsepower units are employed, however, the torque of the engine and the propeller is applied to the steering system. This torque is amplified during turning maneuvers, and for this reason, steering can become exceedingly difficult and tiresome on high-powered boats when operating at higher speeds.
In order to assist in steering of larger outboard motors and inboard/outboard boats, a highly improved steering means is accomplished by using a fin located in the propeller slip stream. The fin reacts with the stream of water from the propeller, and when turned at an angle, torque face is applied to the propeller assembly. Reference may be had to U.S. Pat. No. 3,943,879 entitled "Power Steering System for Boats" for an example of the use of an auxiliary fin located in the propeller stream for steering a boat. Other references to the use of auxiliary fins are found in U.S. Pat. Nos. 3,149,605; 2,993,464; 1,166,749, and 1,540,079.
These devices substantially increase the ease and safety of steering higher-powered boats, but each has a limitation. The devices most commonly employ a fin located rearwardly of the propeller and in the propeller slip stream. The boat steering mechanism is arranged so that when steering control is applied it first moves the fin rather than moving the motor assembly itself. The fin then reacts with the flow of water and applies a turning torque to turn the motor assembly. If the fin fails to achieve the required torque necessary to turn the motor, further actuation of the steering mechanism then engages to turn the motor assembly. Thus, in the system there is a slip arrangement between the steering mechanism and the motor permitting the power assist fin to be turned before steering torque is applied to the motor. This system works exceedingly well when used on a boat traveling in the forward direction and at a fast speed. However, when a boat is traveling at a slow speed, the torque applied to the fin is insufficient. Adequate steering of the boat at slow speeds is accomplished only when the motor assembly itself is turned by the steering mechanism. This means that the operator must overcome a large amount of slack in either direction of rotation of the steering wheel before steering force is applied to the motor assembly. Another problem with the auxiliary finned type power assist steering system is in backing the boat. The fin arrangement is not only ineffective as far as assisting steering, but in fact, works contrary to the desired arrangement for providing steering control.
A third problem exists with the auxiliary fin power assist type steering systems which is less common than the first two mentioned difficulties, and that is, on high-speed boats the power assist fins may actually be out of engagement with the water as the boat rides high upon the propeller. Under these conditions the power assist fins are of no value and sloppy steering is achieved.
An object of the present invention is to provide an improved power steering system for outboard motors and/or inboard/outboard power units which overcomes the problems with existing power steering devices.
More particularly, an object of this invention is to provide an improved power steering system for outboard motors or inboard/outboard power units employing auxiliary power assist fans, including means to automatically couple the boat steering system directly to the motor assembly under conditions wherein the auxiliary fins would be of no advantage.
These general objects as well as other and more specific objects of the invention will be fulfilled in the following description and claims, taken in conjunction with the attached drawings.